甘肃省净初级生产力时空变化特征

Spatial Differences of Net Primary Productivity in Gansu Province

本研究通过改进的光能利用率概念模型(Carnegie-Ames-Stanford Approach,CASA)和MODIS-NDVI数据估算了2000-2010年甘肃省净初级生产力(NPP)的空间分布格局,并结合气候因子,在不同空间和时间尺度上探讨森林生态区、草原生态区、农业生态区和荒漠生态区的NPP变化特征及与气候变化之间的关系。研究表明:①2000-2010年甘肃省NPP的空间分布差异比较显著,总体上呈现东南高西北低,即从东南向西北是逐渐递减的;其中,森林生态区、草原生态区、农业生态区和荒漠生态区的年均NPP分别为580.12 g·cm-2·a-1、380.12 g·cm-2·a-1、280.71 g·cm-2·a-1和83.27 g·cm-2·a-1。②2000-2010年甘肃省NPP显著增加和轻度增加的面积分别占总面积的6.00%和17.49%,NPP显著减少和轻度减少的面积分别占总面积的12.31%和27.07%,NPP有减少的趋势。③以年为尺度,森林生态区和草原生态区主要受温度影响,而降水量是荒漠生态区和农业生态区的主要控制因子;在月尺度上,气候因子对NPP的作用相当;草原生态区和农业生态区分别对月降水量和月均温存在时滞与累积效应,森林生态区和荒漠生态区对降水量或温度不存在时滞与累积效应。④本文认识和了解不同空间和时间尺度上NPP的变化规律,探讨NPP与气候变化之间的相互作用与机理,为生态系统调节起到重要的理论指导意义。

In this study, the spatial distribution of NPP in Gansu Province was simulated by the improving Carnegie-Ames-Stanford Approach （CASA） Model and 2000 -2010 time series data sets of MODIS-NDVI data at 250 m x 250 m spatial resolution. The paper discussed relationship between NPP changing features and climate change of forest, grassland, agriculture and desert ecological regions by combining with meteorological data. The results showed： （~） The variation of the NPP spatial distribution from 2000 to 2010 were significantly different. The high NPP value in the southeast and the low NPP value in northwest, and the average annual NPP of forest, grassland, agriculture and desert regions were 580.12 g · cm-2· a-1 , 380. 12 g· cm-2· a-1, 280.71 g ·cm-2·a 1 and 83.27 -2 . a-i g cm , respectively. （1） The NPP values with the significant increase and the slight increase from 2000 to 2010 accounted for 6.00 % and 17.49 % of the total areas, respectively. And the NPP values with the significant decrease and the slight decrease from 2000 to 2010 accounted for 12.31 % and 27.07 % of the total areas, respectively. But overall, the NPP values showed a decreasing trend. （3） The forest and grassland regions were mainly influenced by the factor of temperature, and the precipitation was the main control factor in desert and agriculture regions in the annual scale. It is consistent with the influences by climate factors in the month scale, compared with the forest and desert regions, the grassland and agriculture regions had the time lag and cumulative effects with climate change. （4） Our objectives were to know and understand the varying pattern of NPP in spatial and temporal scales, and meanwhile to discuss the interaction and mechanism of the relationships of NPP and climate change, finally providing significant support to the ecosystem adjustment.